Preparation

Preheat oven to 350ºF. Grease 8"X8" pan.
Combine cake mix, eggs, water and melted butter in large bowl. Stir until thoroughly blended. Mixture will be thick. Spread in greased pan.
Bake at 350ºF for 24 to 27 minutes or until toothpick inserted in center comes out clean. Cool completely in pan.
Prepare frosting by adding the water and butter to the frosting pouch and mixing until smooth.
Place the large bar onto a cutting board and invert.
Spread the frosting on the upside down bar.
Drizzle melted chocolate (if desired), then cut into bars.